One type of conventional forming machine incorporates a pair of reciprocal gear tracks having teeth which engage a workpiece causing a forming operation to take place. Machines of this type are disclosed by U.S. Pat. Nos. 3,214,951 and 3,793,866.
Another type of forming machine utilizes rotary-forming tools to form a workpiece. A pair of such tools are rotatably supported in a spaced relationship to each other. The periphery of these tools defines the forming face that engages the workpiece to provide the forming operation. U.S. Pat. Nos. 2,886,990 and 3,201,964 disclose forming machines in which substantially the total 360.degree. periphery of each rotary tool defines its forming face. Consequently, a one to one-half revolution of the tools performs a complete forming operation. However, damage or wear to either of the forming faces on one of the tools requires replacement of the tool even though the other forming face is still usable.
This problem is solved in another type of rotary-forming machine disclosed in U.S. Pat. No. 4,045,988 to the same inventor and assigned to the same assignee herein. This patent discloses rotary tools which are mounted on the tool spindles in a manner that permits any one of the tools to be removed and replaced independently of the other tools. Consequently, if one tool wears or is damaged, it can be replaced without requiring replacement of the other tools. A plurality of rotary tools are mounted on each tool spindle in a circumferentially spaced relationship. Each tool includes a partially circular forming face having forming projections that extend about the associated tool spindle axis for an angle less than 180.degree.. Each tool spindle is rotatably mounted by an associated support housing that is slidably mounted by a slideway on a base of the machine. Between the tool spindle support housings, the work spindle supports a workpiece to be formed such that movement of the support housings toward and away from each other allows workpieces of different sizes to be formed. A problem encountered with this device is that during the forming operation the tool spindles tend to move apart, causing imprecise forming of the workpiece.